Soren Knabe, chair of the environmental group Vandpleje Fyn and a member of the Danish Angler’s Association, told the Copenhagen Post that it was the worst possible time for rainbow trout to be released into Danish waters.

“Sea trout are currently coming up into Funen streams to spawn, and sea trout eggs are a favourite food for rainbow trout,” said Mr Knabe, referring to Funen island, south of the farm.

“The escaped rainbow trout will follow right behind the tails of the sea trout and eat their eggs.”

The ecological threat posed by the fish was confirmed by Jon Svendsen, a researcher at Denmark’s National Institute of Aquatic Resources, who spoke to Reuters news agency.

However, an angler who spoke to the agency said it would take four or five days for the escaped fish to adjust to their new environment and begin to bite.

The cargo vessel was en route from the Russian enclave of Kaliningrad, to the east, to the Danish port of Kolding when it crashed on Tuesday.